Current Standards Variability Between Transmit and Receive Modules in Low-Power LoRa Modules

LoRa modules are wireless communication modules used for long-distance wireless communication in applications like the Internet of Things (IoT), remote monitoring, and smart cities. The current requirements for transmit and receive modules in LoRa modules are determined based on application needs and module performance. Typically, the receive current and transmit current are detailed in the module's technical specifications. Each of them has its own standards.

For common LoRa modules, the following standard requirements for receive and transmit currents are often encountered:

Transmit Module Current Requirements: Transmit current requirements are usually higher compared to receive current requirements because transmitting requires more electrical power to meet the power output. Transmit current requirements typically range from tens of milliamperes to several hundred milliamperes. The specific transmit current requirements depend on the module's transmit power, operating frequency, and other technical parameters. In general, higher transmit current results in higher power consumption while transmitting. Therefore, when selecting a transmit module, the focus is mainly on transmit power consumption and current requirements.

Receive Module Current Requirements: In general, LoRa modules have lower receive current requirements, usually ranging from a few milliamperes to tens of milliamperes. The specific receive current requirements depend on the module's operating frequency, receive sensitivity, and other technical parameters. Lower receive current leads to lower power consumption when the module is in standby mode. Receive modules also pay attention to the magnitude of sleep current (static current). Reducing sleep current is essential, especially for battery-powered applications. By reducing sleep current, devices can enter a low-power state when communication or task processing is not required, thereby minimizing battery consumption.

For low-power receive modules, there is often a trade-off between power consumption and performance, such as response time. Low-power modules require more time to wake up the microcontroller. Both power consumption and wake-up time can be balanced using crystal oscillators (XOscillators).

In general, low-power receive modules with good performance have sleep current requirements ranging from several microamperes to tens of milliamperes.

Let's take the LoRaCC68 series low-power LoRa module as an example to explain the transmit module and receive module's current requirements, corresponding to transmit power, operating frequency, receive sensitivity, and sleep current values.

The LoRaCC68 series wireless modules are low-power modules developed by NiceRF. The module has a built-in 64kHz crystal oscillator and can wake up the microcontroller in low-power situations. The module has obtained CE and FCC certifications and is of reference value. The detailed current data for each module is shown in the table below (operating voltage is 3.3V, receive sensitivity is -129dBm, and the maximum output power is 22 dBm or 160mW).

From the table above, it can be seen that the transmit current in the LoRaCC68 module's transmit module is significantly affected by the operating frequency; higher frequencies result in higher current. The receive current in the receive module is related to the crystal oscillator; the passive crystal oscillator has a receive current of less than 5mA.

The sleep current magnitude is related to the startup method, with warm starts having slightly higher sleep currents than cold starts. Additionally, the STDBY_RC mode's sleep current is usually slightly higher than in other clock source modes because the external RC oscillator requires some current to provide a clock signal. In contrast, using other clock sources like crystal oscillators or TCXOs(temperature-compensated crystal oscillators)  can achieve lower static current.

In conclusion, in LoRa modules, the transmit module's transmit current and the receive module's receive current vary based on factors such as transmit power, operating frequency, receive sensitivity, and the mode of oscillation. Low-power modules typically have sleep current requirements ranging from several microamperes to tens of milliamperes, and the specific value depends on the startup method and oscillator used.